Property boundary marker

ABSTRACT

A boundary marker designed to be buried in the ground and constructed with a maximum surface area so as to afford maximum resistance to movement in any direction. The marker is cast from iron in the shape of alternate orthogonal, thin plates so that external forces fracture the plates of the marker rather than move it. The marker is adjustable in length and cast from an iron which is high in cementite so that the marker can be magnetized for easy location.

United States Patent Johnson 1151 3,685,237 [4 1 Aug. 22, 1972 1 PROPERTY BOUNDARY MARKER [72] Inventor: John David Johnson, 1435 3rd Ave.

S., Anoka, Minn. 55303 [22] Filed: Feb. 24, 1970 [21] Appl. No.: 13,476

[52] US. Cl. ..52/98, 52/103, 52/726, 94/l.5, 248/156 [51] Int. Cl ..G01c 15/04, G016 15/06 [58] Field of Search ..52/98, 103, 726, 737-739, 52/104, 105; 94/15; 240/84; 40/145;

[56] References Cited UNITED STATES PATENTS 832,711 10/1906 Weber ..52/738 1,029,404 6/1912 Schumacher.... ..240/84 1,281,062 10/1918 Norvell ..248/156 3,091,997 6/1963 Byrd ..94/1.5 3,349,531 10/1967 Watson ..94/1.5

401,782 4/1889 Howlett ..52/103 482,062 9/l892 McBroom ..52/ 103 1,264,189 4/ 1918 Keator ..52/ 105 1,902,875 3/ 1933 Mason ..52/103 3,126,861 3/ 1964 Sheinwa1d ..52/ 105 3,378,967 4/1968 Baumeister ..52/103 3,602,007 3/1970 Andersson ......94/ 1.5

FORElGN PATENTS OR APPLICATIONS 25,837 3/1903 Switzerland ..52/737 Primary Examiner-Frank L. Abbott Assistant Examinerbeslie A. Braun Attorney-Robert M. Dunning [57] ABSTRACT A boundary marker designed to be buried in the ground and constructed with a maximum surface area so as to afford maximum resistance to movement in any direction. The marker is cast from iron in the shape of alternate orthogonal, thin plates so that external forces fracture the plates of the marker rather than move it. The marker is adjustable in length and cast from an iron which is high in cementite so that the marker can be magnetized for easy location.

8 Claims, 5 Drawing Figures PATiNtEnmsez m2 I 3" 685.237

INVENTOR uo/wv 0/11 10 JOHNSON BY I 8m ATTORNEY PROPERTY BOUNDARY MARKER BACKGROUND OF THE INVENTION In the past, prior art property markers have been constructed from charred wooden poles, large concrete marker stones, pipes driven into the ground, and other such objects which were subject to easy accidental or intentional movement. Many difficulties are inherent in these types of markers. Wooden poles, of course, deteriorate quickly and become virtually impossible to distinguish after a relatively short time. Surface stones or stones'with markers on them are easily moved. Surface stones also present obstructions to surface activity such as farming or the construction of buildings and roads. Concrete markers or metal poles which are buried in the ground are extremely difficult to find and, furthermore, being invisible are often struck by bulldozers, plows, or other equipment operating in the area unaware of the position of the marker. Such collisions usually bend or move the marker in such a way as to make it unclear where the original exact survey point had located the marker. Thus, prior art markers have been very difficult to find, unreliable, too easy to remove and relocate, and in some cases unacceptably short lived. The present invention provides a new type of property boundary marker which completely overcomes all of the above described disadvantages.

SUMMARY OF THE INVENTION Briefly, the present invention contemplates forming a corner marker from cast iron which has a high percentage of cementite in its composition. In this way the marker may be readily magnetized so that it can always be easily located with a conventional dip needle. In addition, the marker is cast so as to have component flat portions disposed in three orthogonal planes providing an extremely high surface area with respect to the weight and size of the marker so that once the marker is buried in the ground it is extremely difficult to move. Furthermore, the three orthogonal flat portions of the marker are cast so as to provide preferred fracture planes whereby the marker will break rather than leave its assigned location if it is struck by a plow, bulldozer, or other external force. The new marker also incorporates spacers to permit a variation in the height of the marker for future alterations and strengthening ribs in various places to protect the marker from particular types of outside forces. Thus, it may be seen that it is an object of the present invention to provide an improved property boundary marker. It is a further object of my invention to provide a marker which is more permanent and less easily moved. Still another object of my invention is to provide a marker which may be magnetized for easy location and which is designed to break away upon external impact rather than leave its assigned location. Other objects and advantages will become apparent upon reference to the following description and drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of a typical assembled embodiment of the present invention.

FIG. 2 is an elevational view of the top half of the FIG. 4 is a side view of the spacer positioned at the top of the assembled marker of FIG. 1.

FIG. 5 shows an impact wrench suitable for disconnecting the various components of the property marker.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 a typical version of the present invention is shown comprising an upper portion 10 and a lower portion 12 which are screwed together and then welded in place. Since the marker is cast from iron it is economically more practical to make it in two portions whenever it exceeds a convenient length. In FIG. 1 it may be seen that the various portions are cast to provide a maximum surface area in three planes. Thus, the upper portion of the marker 10 comprises two end discs 14 and 16 spaced by two plates 22 and 24 which are disposed in one plane and a plate 26 which is orthogonally disposed to plates 22 and 24. Although the preferred embodiment uses orthogonal plates it should be understood that the plates could be positioned in a variety of angles other than ninety degrees. Plates 22, 24, and 26 are separated by cross-shaped plates 21 which are disposed orthogonally to plates 22, 24 and 26. Thus, the marker has extensive surface area facing in all directions so that once the marker is buried in the ground it is extremely difiicult to remove it from the ground or to move it in any direction. Cross-shaped plates are used for plates 21 in order to make it easier to fill dirt in around the marker after it has been inserted into a hole in the ground at the appropriate location. It is apparent from FIG. 1 that the entire structure is cast in such a way as to be easily breakable at certain preferred fracture points. For example, if the marker is struck from the direction indicated by arrow 15, plate 22 will crack 'just below gusset 30 at the point indicated by the number 23. The rest of the marker structure from point 23 down is undisturbed and remains properly positioned to mark the original survey location despite the fact that the marker has been struck by a plow, bulldozer, or other probe device. If a sudden force is applied as indicated by the arrow 17 the marker fractures in the orthogonal direction at the point 25 near the top of plate 26. It should be understood that the preferred embodiment is cast from a brittle cast iron so that the whole structure is relatively easy to fracture as described above. Additionally, the relative amount of cementite in the cast iron is maximized so as to make the entire structure easy to magnetize so as to assist in the future location of the marker with any magnetic sensing device such as a dip needle. In the preferred embodiment this mixture has been found to yield a product which is relatively long lasting, easy to magnetize, and brittle so as to fracture at the desired points. In fact, the preferred embodiment of the marker fractures so easily that reinforcing ribs 28 are provided on both sides of plates 22, 24, and 26 at the center of the plates so as to insure that the marker does not fracture during handling or from other minor disturbances such as frost or overhead traffic.

Any suitable method may be utilized to magnetize the marker for easy location, however, the present invention contemplates subjecting the completed structure to a magnetic field. This method has been found to induce sufiicient magnetism in the marker to make it easy to find at any future date.

In searching for the marker it is common practice to probe for it with a steel rod listening for the metal to metal contact. If the top of the marker of FIG. 1 is struck near its edge it is possible to fracture it along the top of plate 22 in the same manner as if a force were applied from the direction indicated by the arrow 15. Consequently, reinforcing rib 28 is expanded into a gusset 30 on plate 22 so as to prevent fractures resulting from this particular activity. It should be noted that when the device does fracture from some external force, the combination of the vertical plates 22, 24 and 26 with the reinforcing ribs leaves a small raised cross at the center of the marker facilitating a precise location of the survey point even though a portion of the device has been broken away.

Referring now to the lower portion of the marker 12 it may be seen that approximately the same form of construction is used as in the upper portion employing end discs 18 and 20 along with orthogonal vertical plates 40, 41, 42, and 43. As before, the vertical plates are separated by a series of horizontal cross-shaped plates 46, 48, and 50. However, the lower portion 12 is constructed to taper outward at the bottom so as to provide a more stable and balanced marker for easier positioning in the ground during burial. The taper is provided in the preferred embodiment merely as a matter of convenience and is not a necessary element of the present invention.

In use the particular location to be marked is precisely determined and a hole large enough to contain the marker prepared at the location. The marker is buried in the hole with the central small indentation 60 directly underneath the plumb bob of the survey instrument. At this point it is important to note that the invention may be employed in two versions, one of which is buried fairly deep in the ground and which would require only the portions and 12 shown in FIG. 1. The second version may be buried flush with the surface of the ground which surface may be, for example, a road surface. Where the marker is to be flush with the surface a number of spacers 62 and 64 are provided which are used to adjust the height of the marker to be exactly even with the surface of the ground. If the surface height of the ground is changed at a later date as, for example, by resurfacing the road, spacers may be removed or added as required in order to once again level the top of the marker with the new surface. To better understand how the spacers are connected together reference should be had to FIGS. 2, 3 and 4.

In FIG. 2 the upper portion of the marker 10 is shown in elevation with all of the elements numbered identically to the corresponding elements of FIG. 1. Spacer 62 is connected to disc 14 at the top of portion 10. The configuration of this connection may be seen by reference to FIG. 3 which shows the top of disc 14. In the top of disc 14 is a hole 70 which has two inwardly extending lips 72 and 74. Spacer disc 62, shown in FIG. 4, has an extension 76 which has two outwardly extending lugs 78 and 80 thereon. Lugs 78 and 80 and lips 72 and 74 are slightly inclined to permit a screw type con tact. Spacer 62 is connected to disc 14 by inserting the extension 76 with lugs 78 and 80 into hole 70 and rotating spacer disc 62 so as to screw lugs 78 and 80 into and underneath inwardly extending lips 72 and 74 until wedged in place. This type of connection insures that the center of spacer disc 62 is properly aligned with the center of the marker and the center of disc 14. This technique is also used to mount disc 16 to disc 18 in FIG. 1 so as to connect portions 10 and 12 together. However, in the connection of FIG. 1 the discs are additionally welded to insure that the two portions of the marker do not come apart. The connection between portions 10 and 12 employs an extension 82 on disc 16 which has two radially extending lugs 84 and 86.

Referring again to FIG. 1, it may be seen that the last top spacer 64 is slightly different in that its upper surface is provided with an indentation 60 indicating the center of the marker and two holes and 92. Holes 90 and 92 are designed to accept a pair of lugs 94 and 96 on an impact wrench 98 as shown in FIG. 5. The assembly of portion 10 with a series of spacers such as spacer 62 and a cap 64 is intentionally designed to rust together so as to form a tight bond which is not disturbed by surface traffic and other minor disturbances. Separation of the spacers and the cap may be achieved only by inserting lugs 94 and 96 of the impact wrench into holes 90 and 92 and applying a sudden impact to torque the wrench.

From the foregoing it may be seen that a much improved boundary marker has been provided which will reliably indicate a predetermined location even though suflering large external disturbances. In addition, a marker has been provided which may be adjustable in height, easily magnetized to assist future location, and which is very difficult to intentionally or accidentally move. These advantages have been afforded by the use of a high surface area structure constructed from a particular type of cast iron which is brittle and easily magnetized. However, the exact structure shown in the drawings is not necessary to the objects of the invention. Any brittle material could be satisfactorily employed including a number of other metals and ceramics, and the particular configuration of the plates in the vertical and horizontal planes may be varied widely without departing from the spirit and scope of the present invention. Since many variations are possible which cannot be described in detail, I do not intend to be bound to the specific structure shown in the drawings which includes substantially rectangular plates and cross-shaped plates except as defined by the appended claims.

I claim:

1. A property boundary marker adapted to be buried comprising a cast iron column shaped so as to have along its length a plurality of weak zones which comprise preferred fracture points in which the weak zones in said column comprise first, second, and third sets of fracturable flat plates, each said plate having a large surface area, said first flat plates alternate with said second flat plates in an end to end nonaligned angular relationship and in which each adjoining first and second flat plates are separated by a third flat plate disposed in a plane generally orthogonal to said first and second flat plates.

2. The apparatus of claim 1 in which said first, second, and third sets of flat plates are disposed in three generally orthogonal planes respectively so as to present a maximum surface area in all directions.

3. The apparatus of claim 2 including gussets on said plates operable to further define and localize said preferred fracture points.

6 4. The apparatus of claim 2 including reinforcing ribs- 7. The apparatus of claim 6 including spacer blocks on said first n Second Plates generally P adapted to connect to the end of one of said multiple lel to and contiguous to the central axis of said column. ti so as t vary the length of said column.

5. The apparatus of claim 4 in which said third set of 8. The apparatus f claim 7 in which said spacer plates are generally cross-shaped.

6. The apparatus of claim 5 in which said column comprises multiple portions, each portion terminated with a base plate adapted to connect to the base plate of another portion.

5 blocks are designed to rust solidly to the marker so as to resist loosening until removed with an impact wrench. 

1. A property boundary marker adapted to be buried comprising a cast iron column shaped so as to have along its length a plurality of weak zones which comprise preferred fracture points in which the weak zones in said column comprise first, second, and third sets of fracturable flat plates, each said plate having a large surface area, said first flat plates alternate with said second flat plates in an end to end nonaligned angular relationship and in which each adjoining first and second flat plates are separated by a third flat plate disposed in a plane generally orthogonal to said first and second flat plates.
 2. The apparatus of claim 1 in which said first, second, and third sets of flat plates are disposed in three generally orthogonal planes respectively so as to present a maximum surface area in all directions.
 3. The apparatus of claim 2 including gussets on said plates operable to further define and localize said preferred fracture points.
 4. The apparatus of claim 2 including reinforcing ribs on said first and second plates running generally parallel to and contiguous to the central axis of said column.
 5. The apparatus of claim 4 in which said third set of plates are generally cross-shaped.
 6. The apparatus of claim 5 in which said column comprises multiple portions, each portion terminated with a base plate adapted to connect to the base plate of another portion.
 7. The apparatus of claim 6 including spacer blocks adapted to connect to the end of one of said multiple portions so as to vary the length of said column.
 8. The apparatus of claim 7 in which said spacer blocks are designed to rust solidly to the marker so as to resist loosening until removed with an impact wrench. 